Dental flask



May 4, 1948. N. oPoTow 2,440,910

DENTAL FLASK Filed Dee. 13, 1945 2 sheets-sheet 1 zNVENToR. mggzw@ May 4, 1948. N, OPQTOW 2,440,910

DENTAL FLASK Filed Dec. 13, 1945 2 Sheets-Sheet 2' Patented May 4, T948 DENTAL FLAsK Nathan Opotow, New York, N. Y.V Application December 1s, 1945, serial No. 634,735

2 Claims.

This invention relates to dental flasks used by dentists for forming partial or full artificial dentures. f

In general, artificial dentures of this type are made by investing a model of the jaw structure into the lower portion of a dental flask together with the waxed-up case representing a prototype of the finished denture. The surface of the plaster investing the model is then coated with oil or soap and the upper section of the flask is there# after applied over the lower section and filled with plaster or artificial stone serving as investing material. The cover is applied and the in vesting material is allowed to set. Thereafter, the assembled flask is immersed in boiling water for several minutes whereupon the upper portion of the flask is removed or separated from the lower section, the wax of the waxed-up case having been washed out or softened during the boiling process. Thermoplastic material, such as various acrylates, or any other suitable denture material, is then applied to the space left by the molten wax and the upper portion of the flask is restored, The re-assembled flask is then subjected to pres'- sure in order to force and distribute the plastic material into the space while compressing it to a high density. During the compression process, the flask is re-opened to add denture material, such re-opening usually occurring at least twice to assure an oversupply of plastic denture mateer rial to compensate for curing shrinkage. 'I'he quantity of material applied is such as to retain the flask slightly open even after final pressure.

The above method, while generally practiced throughout the industry, is recognized as involve ing many diiculties and productive of unsatise factory results in a large percentage of cases. In general, the principal objection has been the production of discrepancies between the wax pattern and the cured denture through alteration of the planned occlusion which is caused by the necessity of applying an excessive amount of plastic material to compensate for curing shrinkage.

In order to overcome some of the difficulties inherent in this type of investing, another method, sometimes referred to as a banking procedure, has been practiced. 'I'his method avoids the necessity of separating the teeth and model after the wax has been washed away. It is accomplished by investing the teeth and model in one half of the flask, while banking the plaster around the teeth and model far above the height of the flask portion in which it is invested. The upper portion is formed with a mound of plaster (ci. 12a- 33) in the form of a plunger. and prior to its application to the opposing portion of the flask, the wax is eliminated as previously and the denture material is applied through the lingual sides of the waxed-up case. This method practically assures a suiiicient supply of plastic denture material to compensate for the curing shrinkage, and furthermore, requires no separation of the teeth and model after they have been initially assembled with the waxed-up case in position.

Processing of the artificial denture by the banking method above described has not been generally-adopted in spite of its benefits because of other difliculties which have made its use impractical in many cases. Thus, the banking procedure may be` employed where small partial dentures are required, but it is rarely employed where an extensive partial or a full denture is to be prepared. The principal diflculty has been the fact that the application of pressure to force the plastic material into place and to insure proper density thereof, very often cracks the banked wall of plaster and virtually destroys the denture,

Bearing the foregoing in mind, it is an object of the present invention to provide a dental flask which permits the processing of an artificial denture, either partial or full, by means of a banking process, an-d with the application of extremely high pressure, but wherein the danger of fracturing the built-up plaster or model is virtually eliminated.

Another object of this invention is to provide a dental flask adapted to permit banking procedures wherein free access, both physical and visual, to the invested teeth is permitted so that the plastic denture material can be applied with ease, accuracy and precision.v

Another object of this invention is to provide a dental flask which permits utilization of banking procedures together with its benefits above Adescribed and which is further capable of functioning as an ordinary dental flask so as to permit processing of artificial dentures by methods other than banking.

Still another object of this invention is to enable the wax of the waxed-up case to be adequately removed where the boiling process has not completely done'so. Allied with this object is the provision of means toy permit the effective removal of any foreign material from the invested model and teeth before the application of denture material. Similarly, such means permit the replacement of a tooth loosened during the washing out process. y

A further object of this invention is to permit such processingof dentures whereinextremely Other objects of my invention will be apparentA from the following description, it being Vunderstood that the above general statements of the u objects of my invention are intended to describe and not to limit it in any manner.

Referring to the drawings, Fig. l is a disassembled or exploded View of the improvedflask.

Fig. 2 is a similar view illustratingy the flask partly assembled and in the position wherein the denture material is applied.

Fig. 3 is a perspective View of the completely assembled iiask.

Eig. 4 Lis an. elevational view ofA an investing portion of a dental flask constructed according tothe principles of theinvention herein butillus-v trating `a. modified embodiment thereof.

Fig. 5 is a composite Aview in perspective ofthe improved flask illustrating the condition of the invested model and teeth prior tothe application of the denture material. l

The flask comprises the `base section orreceptacle lil which may have a conventional knock-.out block Illa to facilitate removal of the finished denture.v Base Ifis formed with a, Wall il surrounding the same. Openings I2 formed in wall Il are adapted to. receive lugs Iil of theintermediate section I4, but any conventional connection is suitable.

Intermediate section 'Ill is U-shaped so that the rear portion thereof is cut away. Thus, referring to Fig. 2, it will be4 observed that the wallA portion AI5 of the base I0 does not support any portion ofintermedia-te section I4. A cover section AII having openings I.'I- which fit over the pins l`3, as do the openings l2, is formed with body openings I8. Body openings iI8 may have bevelledwalls I9 so that excessive investing matextiel1 may be 4forced through andv the Vmaterial maybe )securely grippedv by the beveled Walls I9 when the cover section IB is applied.

Cover section I6 is formed with an oiset mem'-V ber lin 'the form of depending flange 20 which supplies'the closing wall for the U-shaped intermediate section I4 and may rest upon Wall` sectionk I5 as shown in Fig.'3.

In order to utilize the improved dental flask, the teeth in the form of a waxed'up'-case,.and the model' of the Vjaw structurer are invested in both the base section I0 and intermediate sec tion I4 when assembled,as illustrated in Fig. 2. Theinvestment inthe combined base andi-titer# mediate sections is then coated with oil, soap er any'other separating material and more plaster is applied, the top section I6 beingfapplied thereon. After setting, the plaster last applied vis retained by the cover section I6 and assumes lthe shape of a mound'l which functions as a plunger meansfor compressing the artificial denture material thereafter applied.

When the vcover :section -I-6 together with the plaster-.filled lflask "enclosing the 'model kand waxed-:up vease is assembled, and the plaster-has set, theflask is heated so as tofboil out or soften the wax which retained the artificial teeth on the! model. Theseteethwill now` be retainedin the plaster l'o'f the inter-mediate. section -Idrsoa 75 that when the flask is separated it will assume the appearance illustrated in Fig. 5.

Referring to Fig. 5, the base section I0 has the set plaster 2| therein which secures the intermediate section I4 thereto. In the particular case illustrated, the cuspid teeth of the patient are not being replaced with articial teeth since it may be assumed that his natural teeth are satisfactory. The particular case of Fig. 5 is illustrated tddernonstrat'e the versatility of the improved flask, but it is* apparent that practically any type of partial denture as well as a complete denture can be accommodated thereby. The wax having been boiled away, the teeth '22 are separated by an air space 23 from the Vmodel gum ridges 24. It is now possible to easily remore any wax notboiled away or foreign objects. Similarly, teeth loosened by the washingout'process may be restored. It will be observed in Fig. 5 that the artificial denture material may now rbe applied with the utmost ease and eiliciencysince ,the entirev spacei is fully accessible both visually and physically from the rear opene ing afforded by theintermediate section Ill. The cutaway portion of intermediate section I4 is referred to as the rear opening. because, in effect, itis-formed inthe rear Wall of the flask. It is through thisopeningthat the rear sides of the teethmaybe seen as illustrated in Fig. 5. Thus, any peculianformation of the gum ridges can be taken into consideration and the denture material applied accordingly.v Itl will be observed, furthermore, thatthe teeth 22 are not only sur rounded and protected by the plaster 2l, but are further-'bachedup by the U-shaped section I4. Accordingly, the operator may apply the denture material compact/ly and firmly into all spaces left byr theboiled-out Vwainthrough the lingual sides of the teeth-the open wall of U-shaped inter' mediate section I4 functioning as a window and offering no obstruction'in the procedure.

It' will be observed that a sufficient quantity of denture material to compensate for curing shrinkagecan be applied without risking any change in the cured denture, since the teeth and model are never` sepa-rated after investment. The cover 'section II'with the set plaster 25 forming a mound thereon; is re-applied to the remainder ofV the flask and the assemblage is subjected to pressure whereuponv the mound or plunger 25 compresses the plastic 'denture material so that it'fills the space 23 satisfactorily and with sufficient density. f The degree of compression can be very great, if desired, without fracturing the plasterV investment, sincek the U-shaped intermediate section Ill provides a firm backing for the teeth and plaster `behind it. After the artificial denture material'has been applied as above set forth, the denture is'removed in the usual manner. The application of an eXtreme over-supply of "denture material ismade possible to assure suflicient compression and density without altering the planiiedocclus'ion.

It'will be apparent that the improved dental ask'can also be utilized for investment procedures' wherein the artificial teeth are retained in the removed section, if this procedure is desired.

VIntermediate'section 'Iiserves a further purpose'in that it facilitates the removal of the finished denture and the plaster therefrom This` follows by virtue'ofthe fact that it is separable fom basesection I0 'andits area which bounds the plaster is decreased due to the open wall;

'It' will be further noted that the base receptacle I together with the intermediate section I 4 constitute the lower model investing portion in that these are assembled and function as a unit when the model is set therein and they may very well be made in one piece except that their separability is of advantage in removing the nished denture.

Referring to Fig. 4, the lower model investing portion comprises the base receptacle 26 and the modified intermediate section 21. Intermediate section 21 is formed with the closing portion 28 which in the former embodiment was part of the base receptacle. The embodiment of Fig. 4 is an exact functional duplicate of the lower model investing portion as illustrated in Fig. 2 except that the portion 28 serves as a strengthening member for intermediate section 21 and prevents distortion thereof. The nal separation between base receptacle 26 and intermediate member 2'! is, of course, at the line 29.

`I have shown a preferred embodiment of my invention, but it is obvious that numerous changes and omissions may be made therefrom without departing from its spirit.

I claim:

1. A dental flask comprising a lower model investing portion, a rear wall of said lower portion being cut away at its upper half, said cut away portion extending substantially across the entire rear wall of the ask so as to permit lateral access to the interior of said lower portion, a cover portion adapted to be assembled with said lower portion so as to form a complete ask, and a depending ange on said cover portion having the same dimensions as said cut away portion so as to nest therein and close the opening formed by said cut away portion.

2. A dental flask comprising a base receptacle, a U-shaped intermediate section fitted thereto so as to form a lower model investing portion having an upper section cut away in a rear Wall thereof, a cover portion for said flask, a depending flange on said cover portion, said cover portion being fitted to said intermediate section and base receptacle whereby said cover section may be caused to overlie said intermediate section and said depending ilange may be maintained substantially adjacent said base receptacle so as to cover said cut-away section.

NATHAN OPOTOW.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Malsch Jan. 30, 1940 

